Displaying publications 1 - 20 of 89 in total

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  1. Fulltext Serotype prevalence of Streptococcus pneumoniae in Malaysia - the need for carriage studies
    McNeil HC, Clarke SC
    Med J Malaysia, 2016 Jun;71(3):134-8.
    PMID: 27495888
    Pneumococcal disease, caused by the bacterium Streptococcus pneumoniae, is a major burden to global health. Although the World Health Organisation (WHO) strongly recommends the inclusion of pneumococcal conjugate vaccines in national immunisation programmes (NIP's) worldwide, this has not occurred in many countries in the WHO South East Asia and Western Pacific regions - particularly longstanding middle-income countries. It is widely accepted that carriage of S. pneumoniae is a precursor to developing any pneumococcal disease. The reduction in pneumococcal disease from vaccine serotypes (VT) following widespread implementation of the pneumococcal conjugate vaccine (PCV) is believed to be through the direct immunogenic protective effect of immunised individuals as well as indirectly through herd immunity diminishing the incidence of disease in nonimmunised individuals. In Malaysia, pneumococcal disease is not included in national surveillance programmes and although PCVs have been licensed, they have not been included in the NIP. Hence, the vaccine is only available privately and the majority of the population is not able to afford it. There is an urgent need to develop surveillance programmes in Malaysia to include pneumococcal serotype data from carriage and invasive disease so that it may help guide national vaccine policy prior to a decision being taken on the inclusion of PCVs in the NIP.
    Matched MeSH terms: Streptococcus pneumoniae*
  2. Fulltext Prevalence of macrolide resistance and in vitro activities of six antimicrobial agents against clinical isolates of Streptococcus pneumoniae from a multi-center surveillance in Malaysia
    Jeevajothi Nathan J, Mohd Taib N, Mohd Desa MN, Masri SN, Md Yasin R, Jamal F, et al.
    Med J Malaysia, 2013 Apr;68(2):119-24.
    PMID: 23629556 MyJurnal
    The in vitro activities of 6 antimicrobial agents against clinical isolates of Streptococcus pneumoniae (pneumococci) were investigated and the erythromycin minimum inhibitory concentrations (MICs) were correlated with the two major macrolide resistance determinants, mef(A) and erm(B). MICs of commonly used antibiotics as well as the presence of macrolide resistance determinant genes in all isolates were tested. Seventy one pneumococcal isolates collected at Institute for Medical Research (IMR) were included in this study. Phenotypic characterization, MIC determination using E-test strips and polymerase chain reactions for antibiotic resistance determination were included. Among the isolates, 25 (35.2%) isolates were erythromycin susceptible, 3 (4.2%) were intermediate and 42 (60.6%) were resistant. Fifty three isolates (74.7%) were found with mef(A) alone, 15 (21.1%) isolates with erm(B) + mef(A) combination and 3 (4.2%) isolates with none of the two genes. The in vitro activity of penicillin, amoxicillin clavulanic acid, ceftriaxone and cefotaxime is superior to trimethoprim-sulfamethoxazole and erythromycin. In conclusion, pneumococcal isolates in this study were highly susceptible to penicillin with very low MICs. However, a very high prevalence rate of erythromycin resistance was observed. Erythromycin resistant S. pneumoniae isolates with both mef(A) and erm(B) showed very high MICs ≥256 μg/mL.
    Matched MeSH terms: Streptococcus pneumoniae*
  3. Fulltext The Streptococcus pneumoniaeyefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation
    Chan WT, Domenech M, Moreno-Córdoba I, Navarro-Martínez V, Nieto C, Moscoso M, et al.
    Toxins (Basel), 2018 09 18;10(9).
    PMID: 30231554 DOI: 10.3390/toxins10090378
    Type II (proteic) toxin-antitoxin systems (TAs) are widely distributed among bacteria and archaea. They are generally organized as operons integrated by two genes, the first encoding the antitoxin that binds to its cognate toxin to generate a harmless protein⁻protein complex. Under stress conditions, the unstable antitoxin is degraded by host proteases, releasing the toxin to achieve its toxic effect. In the Gram-positive pathogen Streptococcus pneumoniae we have characterized four TAs: pezAT, relBE, yefM-yoeB, and phD-doc, although the latter is missing in strain R6. We have assessed the role of the two yefM-yoeB and relBE systems encoded by S. pneumoniae R6 by construction of isogenic strains lacking one or two of the operons, and by complementation assays. We have analyzed the phenotypes of the wild type and mutants in terms of cell growth, response to environmental stress, and ability to generate biofilms. Compared to the wild-type, the mutants exhibited lower resistance to oxidative stress. Further, strains deleted in yefM-yoeB and the double mutant lacking yefM-yoeB and relBE exhibited a significant reduction in their ability for biofilm formation. Complementation assays showed that defective phenotypes were restored to wild type levels. We conclude that these two loci may play a relevant role in these aspects of the S. pneumoniae lifestyle and contribute to the bacterial colonization of new niches.
    Matched MeSH terms: Streptococcus pneumoniae/physiology*
  4. Fulltext Hyaluronatelyase production by Streptococcus pneumoniae isolated from patients and carriers
    Yusof HA, Desa M NM, Masri SN, Malina O, Jamal F
    Trop Biomed, 2015 Sep;32(3):413-8.
    PMID: 26695201 MyJurnal
    Hyaluronatelyase produced by various microorganisms are capable of degrading hyaluronic acid in connective tissues and initiating the spread of infection by opening an access for the pathogen into host tissues. The present study attempts to determine the distribution of hyaluronatelyase-producing Streptococcus pneumoniae among invasive, non invasive and carriage isolates, and correlate it with the clinical sources, year of isolation, colonial morphology and their serotypes. A total of 100 isolates from various clinical samples were selected and screened for hyaluronatelyase production and presence of the encoding SpnHyl gene. All isolates possessed SpnHyl gene. Ninety-six isolates including 34 carriage isolates were positive for production of hyaluronatelyase. Four hyaluronatelyase-negative isolates were from blood (2 isolates) and sputum (2 isolates). No significant association was detected among hyaluronatelyase production and bacterial characteristics except for colonial morphology (p = 0.040). High percentages of hyaluronatelyase production in these isolates suggest their possible role as human pathogens.
    Matched MeSH terms: Streptococcus pneumoniae/enzymology*; Streptococcus pneumoniae/genetics; Streptococcus pneumoniae/isolation & purification
  5. Fulltext Evaluation of PCR-based approach for serotype determination of Streptococcus pneumoniae
    Shakrin NN, Balasubramaniam SD, Yusof HA, Mastuki MF, Masri SN, Taib NM, et al.
    Trop Biomed, 2013 Jun;30(2):338-44.
    PMID: 23959499 MyJurnal
    Determination of Streptococcus pneumoniae serotypes is essential for epidemiological surveillance. Therefore accurate, reliable and cost effective serotyping method is crucial. In this study, we determined the serotypes of 41 pneumococcal isolates recovered from human anterior nares by multiplex Polymerase Chain Reaction (PCR) utilizing published primers. The data was then compared with conventional serology using latex agglutination (LA) and the Quellung reaction. Based on the PCR-approach, 8 different serogroups/serotypes were detected with one isolate classified as non-typeable (cpsA-negative). In reference to the serology-based data, the results were in agreement except for one isolate. For the latter isolate, the LA and Quellung tests failed to show a reaction but the PCR-approach and sequencing identified the isolate as serogroup 15B/C. Based on this experimental setting, we found that the PCR-approach for pneumococcal serotypes determination is reliable to serve as the alternative for determining the pneumococcal serotyping.
    Matched MeSH terms: Streptococcus pneumoniae/classification*; Streptococcus pneumoniae/genetics*; Streptococcus pneumoniae/isolation & purification
  6. Fulltext Detection rate of Pneumococcal Pneumonia using the Urine Antigen Kit BinaxNow Streptococcus Pneumoniae Test: a prospective cohort study in a Tertiary Hospital in Malaysia
    Mohamed Faisal AH, Petrick P, Andrea YL Ban, Roslina AM
    International Medical Journal Malaysia, 2017;16(1):29-36.
    MyJurnal
    Pneumococcal pneumonia is the commonest type of bacterial pneumonia worldwide. In Malaysia, the reported incidence of pneumococcal pneumonia is low. This may be due to poor sensitivity of conventional methods. The use of BinaxNOW, a urinary antigen test for Streptococcus pneumoniae can aid in the diagnosis of pneumococcal pneumonia.
    Matched MeSH terms: Streptococcus pneumoniae
  7. Overview of the disease burden of invasive pneumococcal disease in Asia
    Bravo LC, Asian Strategic Alliance for Pneumococcal Disease Prevention (ASAP) Working Group
    Vaccine, 2009 Dec 9;27(52):7282-91.
    PMID: 19393708 DOI: 10.1016/j.vaccine.2009.04.046
    This paper represents a collaborative effort by the Asian Strategic Alliance for Pneumococcal Disease Prevention (ASAP) Working Group to collate data on the disease burden due to invasive pneumococcal disease (IPD) in participating Asian countries and territories; namely, Hong Kong, India, Indonesia, Korea, Macau, Malaysia, Pakistan, the Philippines, Singapore, Sri Lanka, Taiwan and Thailand. A review of both published and unpublished data revealed that the incidence of IPD in some countries is well documented by way of large, long-duration studies, while in other countries, much of the available data have been extrapolated from international studies or have come from small population studies of limited geographical coverage. This paper confirms that data regarding the incidence of IPD in Asia are grossly lacking and reinforces the need for urgent and more substantial studies.
    Matched MeSH terms: Streptococcus pneumoniae/classification
  8. Childhood invasive pneumococcal disease: a hospital-based study from Malaysia
    Lim LH, Lee WS, Parasakthi N
    J Paediatr Child Health, 2007 May;43(5):366-9.
    PMID: 17489826
    New conjugate vaccine for Streptococcus pneumoniae has been introduced in Malaysia recently. Information on infection due to S. pneumoniae in Malaysian children is scarce. We conducted a retrospective chart review of childhood invasive pneumococcal disease (IPD) presented to a single centre in Malaysia.
    Matched MeSH terms: Streptococcus pneumoniae/pathogenicity*
  9. An integrated paper-based sample-to-answer biosensor for nucleic acid testing at the point of care
    Choi JR, Hu J, Tang R, Gong Y, Feng S, Ren H, et al.
    Lab Chip, 2016 Feb 7;16(3):611-21.
    PMID: 26759062 DOI: 10.1039/c5lc01388g
    With advances in point-of-care testing (POCT), lateral flow assays (LFAs) have been explored for nucleic acid detection. However, biological samples generally contain complex compositions and low amounts of target nucleic acids, and currently require laborious off-chip nucleic acid extraction and amplification processes (e.g., tube-based extraction and polymerase chain reaction (PCR)) prior to detection. To the best of our knowledge, even though the integration of DNA extraction and amplification into a paper-based biosensor has been reported, a combination of LFA with the aforementioned steps for simple colorimetric readout has not yet been demonstrated. Here, we demonstrate for the first time an integrated paper-based biosensor incorporating nucleic acid extraction, amplification and visual detection or quantification using a smartphone. A handheld battery-powered heating device was specially developed for nucleic acid amplification in POC settings, which is coupled with this simple assay for rapid target detection. The biosensor can successfully detect Escherichia coli (as a model analyte) in spiked drinking water, milk, blood, and spinach with a detection limit of as low as 10-1000 CFU mL(-1), and Streptococcus pneumonia in clinical blood samples, highlighting its potential use in medical diagnostics, food safety analysis and environmental monitoring. As compared to the lengthy conventional assay, which requires more than 5 hours for the entire sample-to-answer process, it takes about 1 hour for our integrated biosensor. The integrated biosensor holds great potential for detection of various target analytes for wide applications in the near future.
    Matched MeSH terms: Streptococcus pneumoniae*
  10. Fulltext Penicillin resistant pneumococcus
    Jamal F, Tirathram M, Hussin Z
    Med J Malaysia, 1983 Jun;38(2):102-3.
    PMID: 6621437
    The isolation of a penicillm. resistant strain of Streptococcus pneumoniae is being reported and indicates the need to screen pneumococcal isolates for resistance towards antibiotics.
    Matched MeSH terms: Streptococcus pneumoniae/drug effects*
  11. Fulltext International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease
    Gladstone RA, Siira L, Brynildsrud OB, Vestrheim DF, Turner P, Clarke SC, et al.
    Vaccine, 2022 Feb 11;40(7):1054-1060.
    PMID: 34996643 DOI: 10.1016/j.vaccine.2021.10.046
    BACKGROUND: Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them.

    METHODS: Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating.

    RESULTS: Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0-2 SNPs) with the common ancestor dated around 2017.

    CONCLUSION: The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.

    Matched MeSH terms: Streptococcus pneumoniae*
  12. Fulltext Genetic regulation of the yefM-yoeB toxin-antitoxin locus of Streptococcus pneumoniae
    Chan WT, Nieto C, Harikrishna JA, Khoo SK, Othman RY, Espinosa M, et al.
    J Bacteriol, 2011 Sep;193(18):4612-25.
    PMID: 21764929 DOI: 10.1128/JB.05187-11
    Type II (proteic) toxin-antitoxin systems (TAS) are ubiquitous among bacteria. In the chromosome of the pathogenic bacterium Streptococcus pneumoniae, there are at least eight putative TAS, one of them being the yefM-yoeB(Spn) operon studied here. Through footprinting analyses, we showed that purified YefM(Spn) antitoxin and the YefM-YoeB(Spn) TA protein complex bind to a palindrome sequence encompassing the -35 region of the main promoter (P(yefM2)) of the operon. Thus, the locus appeared to be negatively autoregulated with respect to P(yefM2), since YefM(Spn) behaved as a weak repressor with YoeB(Spn) as a corepressor. Interestingly, a BOX element, composed of a single copy (each) of the boxA and boxC subelements, was found upstream of promoter P(yefM2). BOX sequences are pneumococcal, perhaps mobile, genetic elements that have been associated with bacterial processes such as phase variation, virulence regulation, and genetic competence. In the yefM-yoeB(Spn) locus, the boxAC element provided an additional weak promoter, P(yefM1), upstream of P(yefM2) which was not regulated by the TA proteins. In addition, transcriptional fusions with a lacZ reporter gene showed that P(yefM1) was constitutive albeit weaker than P(yefM2). Intriguingly, the coupling of the boxAC element to P(yefM1) and yefM(Spn) in cis (but not in trans) led to transcriptional activation, indicating that the regulation of the yefM-yoeB(Spn) locus differs somewhat from that of other TA loci and may involve as yet unidentified elements. Conservation of the boxAC sequences in all available sequenced genomes of S. pneumoniae which contained the yefM-yoeB(Spn) locus suggested that its presence may provide a selective advantage to the bacterium.
    Matched MeSH terms: Streptococcus pneumoniae/genetics*
  13. Genotypic characterization of Streptococcus pneumoniae serotype 19F in Malaysia
    Jeevajothi Nathan J, Mohd Desa MN, Thong KL, Clarke SC, Masri SN, Md Yasin R, et al.
    Infect Genet Evol, 2014 Jan;21:391-4.
    PMID: 24342879 DOI: 10.1016/j.meegid.2013.11.026
    Streptococcus pneumoniae is an epidemiologically important bacterial pathogen. Recently, we reported the antibiotic susceptibility patterns of a limited collection of pneumococcal isolates in Malaysia with a high prevalence of erythromycin resistant strains. In the present study, 55 of the pneumococcal isolates of serotype 19F were further analysed by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The generated genotypic patterns were then correlated with the antibiograms previously reported. Forty-seven different PFGE profiles (PTs) were obtained, showing that the isolates were genetically diverse. MLST identified 16 sequence types (STs) with ST-236 being predominant (58.2%), followed by ST-81 (10.3%). Among the ST-236 isolates, 22 were erythromycin resistant S. pneumoniae (ERSP) and 15 were trimethoprim/sulfamethoxazole (TMP/SMX) resistant, while among ST-81, four isolates were ERSP and two were TMP/SMX resistant. The high prevalence of erythromycin resistant serotype 19F isolates of ST-236 in this study has also been reported in other North and South East Asian countries.
    Matched MeSH terms: Streptococcus pneumoniae/drug effects; Streptococcus pneumoniae/genetics*; Streptococcus pneumoniae/isolation & purification
  14. Comparison of susceptibility test methods to detect penicillin susceptibility in Streptococcus pneumoniae isolates
    Mohd Nasir MD, Parasakthi N
    Malays J Pathol, 2004 Jun;26(1):29-33.
    PMID: 16190104
    The increasing prevalence of penicillin-resistant Streptococuus pneumoniae urges for fast and accurate susceptibility testing methods. This study evaluated the comparability of three commonly used techniques; disk diffusion, E-test and agar dilution, to detect penicillin susceptibility in clinical isolates of S. pneumoniae. Fifty pneumococcal isolates, obtained from patients at the University of Malaya Medical Centre, were selected to include both penicillin-susceptible strains and those that had decreased susceptibility (resistant and intermediate) to penicillin. The minimum inhibitory concentration (MIC) values of penicillin to serve as the reference was determined by the agar dilution method in which, based on the MIC breakpoints recommended by the National Committee for Clinical Laboratory Standards (NCCLS), 27 strains had decreased susceptibility to penicillin with 17 strains resistant and 10 intermediate. Comparing to the agar dilution method, oxacillin disk diffusion test detected all strains with decreased penicillin susceptibility as such while E-test showed a close agreement of susceptibility (92%) of the isolates to penicillin. This confirmed that oxacillin is a good screening test for S. pneumoniae isolates with decreased susceptibility to penicillin while E-test is very reliable for rapid and accurate detection of penicillin susceptibility.
    Matched MeSH terms: Streptococcus pneumoniae/drug effects*; Streptococcus pneumoniae/genetics; Streptococcus pneumoniae/isolation & purification
  15. Antibiotic susceptibility and serotype distribution of Streptococcus pneumoniae in Malaysian children
    Cheong YM, Jegathesan M, Henrichsen J, Wong YH, Ng AJ, Louis A
    J Trop Pediatr, 1988 08;34(4):182-5.
    PMID: 3172328 DOI: 10.1093/tropej/34.4.182
    Matched MeSH terms: Streptococcus pneumoniae/classification; Streptococcus pneumoniae/drug effects*; Streptococcus pneumoniae/isolation & purification
  16. Fulltext Capsular serotype and antibiotic resistance of Streptococcus pneumoniae isolates in Malaysia
    Le CF, Palanisamy NK, Mohd Yusof MY, Sekaran SD
    PLoS One, 2011;6(5):e19547.
    PMID: 21603602 DOI: 10.1371/journal.pone.0019547
    BACKGROUND: Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations.
    METHODOLOGY/PRINCIPAL FINDINGS: A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S. pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia.
    CONCLUSION/SIGNIFICANCE: Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.
    Matched MeSH terms: Streptococcus pneumoniae/drug effects*; Streptococcus pneumoniae/isolation & purification
  17. In-vitro susceptibilities of Streptococcus pneumoniae strains isolated in Malaysia to six antibiotics
    Rohani MY, Parasakthi N, Raudzah A, Yasim MY
    J Antimicrob Chemother, 1999 Dec;44(6):852-3.
    PMID: 10590295
    Matched MeSH terms: Streptococcus pneumoniae/drug effects*; Streptococcus pneumoniae/isolation & purification
  18. Antimicrobial resistance in Streptococcus pneumoniae: an overview
    Appelbaum PC
    Clin Infect Dis, 1992 Jul;15(1):77-83.
    PMID: 1617076
    Clinical resistance to penicillin in Streptococcus pneumoniae was first reported by researchers in Boston in 1965; subsequently, this phenomenon was reported from Australia (1967) and South Africa (1977). Since these early reports, penicillin resistance has been encountered with increasing frequency in strains of S. pneumoniae from around the world. In South Africa strains resistant to penicillin and chloramphenicol as well as multiresistant strains have been isolated. Similar patterns of resistance have been reported from Spain. Preliminary evidence points to a high prevalence of resistant pneumococci in Hungary, other countries of Eastern Europe, and some countries in other areas of Europe, notably France. In the United States most reports of resistant pneumococci come from Alaska and the South, but resistance is increasing in other states and in Canada. Pneumococcal resistance has also been described in Zambia, Japan, Malaysia, Pakistan, Bangladesh, Chile, and Brazil; information from other African, Asian, and South American countries is not available. The rising prevalence of penicillin-resistant pneumococci worldwide mandates selective susceptibility testing and epidemiological investigations during outbreaks.
    Matched MeSH terms: Streptococcus pneumoniae/classification; Streptococcus pneumoniae/drug effects*
  19. Acanthamoeba castellanii interactions with Streptococcus pneumoniae and Streptococcus pyogenes
    Siddiqui R, Yee Ong TY, Jung SY, Khan NA
    Exp Parasitol, 2017 Dec;183:128-132.
    PMID: 28823705 DOI: 10.1016/j.exppara.2017.08.005
    Among the genus Streptococcus, S. pyogenes and S. pneumoniae are the major causes of pharyngitis, impetigo, pneumonia and meningitis in humans. Streptococcus spp. are facultative anaerobes that are nutritionally fastidious, yet survive in the environment and target the predisposed population. Antibacterial disinfectants have been partially effective only, indicating the need for novel preventative measures and to understand mechanisms of bacterial resistance. Acanthamoeba is a free-living protist that is known to harbour microbial pathogens, provide shelter, and assist in their transmission to susceptible population. The overall aim of this study was to determine whether S. pyogenes and S. pneumoniae can interact with A. castellanii by associating, invading, and surviving inside trophozoites and cysts. It was observed that both S. pyogenes and S. pneumoniae were able to associate as well as invade and/or taken up by the phagocytic A. castellanii trophozoite. Notably, S. pyogenes and S. pneumoniae survived the encystation process, avoided phagocytosis, multiplied, and exhibited higher recovery from the mature cysts, compared with the trophozoite stage (approximately 2 bacteria per amoebae ratio for cyst stage versus 0.02 bacteria per amoeba ration for trophozoite stage). As Acanthamoeba cysts are resilient and can disperse through the air, A. castellanii can act as a vector in providing shelter, facilitating growth and possibly genetic exchanges. In addition, these interactions may contribute to S. pyogenes and S. pneumoniae survival in harsh environments, and transmission to susceptible population and possibly affecting their virulence. Future studies will determine the molecular mechanisms associated with Acanthamoeba interactions with Streptococcus and the evolution of pathogenic bacteria and in turn expedite the discovery of novel therapeutic and/or preventative measures.
    Matched MeSH terms: Streptococcus pneumoniae/growth & development; Streptococcus pneumoniae/physiology*
  20. Fulltext Comparative genomic analysis of ten clinical Streptococcus pneumoniae collected from a Malaysian hospital reveal 31 new unique drug-resistant SNPs using whole genome sequencing
    Jindal HM, Ramanathan B, Le CF, Gudimella R, Razali R, Manikam R, et al.
    J Biomed Sci, 2018 Feb 15;25(1):15.
    PMID: 29448938 DOI: 10.1186/s12929-018-0414-8
    BACKGROUND: Streptococcus pneumoniae or pneumococcus is a leading cause of morbidity and mortality worldwide, specifically in relation to community-acquired pneumonia. Due to the overuse of antibiotics, S. pneumoniae has developed a high degree of resistance to a wide range of antibacterial drugs.

    METHODS: In this study, whole genome sequencing (WGS) was performed for 10 clinical strains of S. pneumoniae with different levels of sensitivity to standard antibiotics. The main objective was to investigate genetic changes associated with antibiotic resistance in S. pneumoniae.

    RESULTS: Our results showed that resistant isolates contain a higher number of non-synonymous single nucleotide polymorphisms (SNPs) as compared to susceptible isolates. We were able to identify SNPs that alter a single amino acid in many genes involved in virulence and capsular polysaccharide synthesis. In addition, 90 SNPs were only presented in the resistant isolates, and 31 SNPs were unique and had not been previously reported, suggesting that these unique SNPs could play a key role in altering the level of resistance to different antibiotics.

    CONCLUSION: Whole genome sequencing is a powerful tool for comparing the full genome of multiple isolates, especially those closely related, and for analysing the variations found within antibiotic resistance genes that lead to differences in antibiotic sensitivity. We were able to identify specific mutations within virulence genes related to resistant isolates. These findings could provide insights into understanding the role of single nucleotide mutants in conferring drug resistance.

    Study site: University Malaya Medical Centre (UMMC)
    Matched MeSH terms: Streptococcus pneumoniae/genetics*; Streptococcus pneumoniae/isolation & purification
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